JP2524779Y2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus provided with a cooling device for cooling at least an optical system.

<Prior Art> An image forming apparatus includes an optical system and a heating and fixing unit as heat-generating parts inside the image forming apparatus. Among them, when the temperature of the optical system becomes high, the durability of a light source or the like deteriorates. It has a cooling device.

A conventional image forming apparatus (80) equipped with such a cooling device is divided into an upper body (82) and a lower body (83) by a partition plate (81) as shown in FIG. An original platen (84) on which the original is placed
An optical system (85) for exposing and scanning the original is provided below the original table (84). On the other hand, the lower body (83) has a copy processing section (87) centered on the photosensitive drum (86).
A paper transport section (90) for taking out the paper from the paper feed cassette (88), sending the paper to the copy processing section (87), and sending the paper after the original image is transferred to the heat fixing section (89); A heating / fixing unit (89) is provided downstream of the paper carrying unit (90) and heats and fixes the original image transferred to the paper and then discharges it to the tray (91). . A sirocco fan (92) is provided in a part of the partition plate (81), and air in the upper main body (82) is exhausted through an exhaust hole (93) provided above the tray (91). At the same time, the through-hole (95) formed at the lower part of the exhaust duct (94) connected to the exhaust hole (93) allows the heat-fixing section (89)
The surrounding air is also discharged (the flow of these air is indicated by arrows in FIG. 2). In addition, air is introduced into the upper body (82) from the outside air through air intake holes (96) formed on both sides of the upper body (82).

<Problems to be solved by the invention> However, in the above-described image forming apparatus (80), the hot air that has cooled around the heating and fixing unit (89) rises and is exhausted through the through holes (95). Therefore, when the paper passes through the heat-fixing unit (89), the vaporized water vapor evaporates from the guide plate (97) provided above the heat-fixing unit (89).
And water droplets that adhere to parts near the surface and form water droplets, and the water droplets fall on paper before and after fixing, causing a problem that the image in that portion disappears or bleeding occurs.

<Object of the Invention> The present invention has been made in view of the above problems, and has as its object to provide an image forming apparatus in which an image formed on a sheet is not adversely affected by water droplets.

<Means for Solving the Problems> In order to achieve the above object, the image forming apparatus according to the present invention includes an introduction part for taking in a part or all of the airflow exhausted from the cooling device, and an introduction part for introducing the airflow. An air flow introduced by the unit to the heating and fixing unit, and an air blowing path for further guiding the air flow from the heating and fixing unit to a sheet conveying path;
A discharge port for exhausting the airflow guided to the sheet transport path by the airflow path to the outside of the apparatus; and the only airflow path for guiding the airflow to the paper transport path is the airflow path. It is characterized by the following.

<Operation> In the above configuration, the airflow exhausted from the cooling device is introduced into the air passage by the introduction unit. As a result, after the air flow is once guided to the heating and fixing unit, it is guided to a sheet conveying unit provided upstream of the heating and fixing unit with respect to the sheet conveying direction. Thereafter, the airflow is exhausted outside the machine.

Since at least the optical system is cooled in the cooling device, the airflow exhausted from the cooling device is hot air. Therefore, the warm air is guided to the paper transport unit via the heating and fixing unit, so that the paper on the paper transport path is preheated. As a result, the moisture contained in the paper evaporates to some extent. Therefore, when the paper is subsequently heated by the heat fixing unit, the generation of water vapor can be reduced.

Further, the warm air exhausted from the cooling device is guided to the heating and fixing unit, so that the ambient temperature around the heating and fixing unit increases. Moreover, the warm air does not stay. Therefore, even if water vapor is generated in the heat fixing unit, there is no possibility that water droplets adhere to a guide plate or the like provided around the heat fixing unit.

Further, the air passage for guiding the air flow to the paper transport unit is one.
Since only one is provided, the air flow is guided to the sheet transport section from only one direction. Therefore, it is possible to reliably obtain the pressing force required to press the sheet. As a result, it is possible to prevent the leading end of the sheet from being turned up.

<Example> Next, an example of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic view showing an embodiment of the image forming apparatus according to the present invention. The upper body (1) of the image forming apparatus (1) having a contact glass (11) and a document holder (12) on the upper surface.
3) It has an optical system (2) inside, and a copy processing section (3), a paper transport section (4), a heat fixing section (5), and a suction fan (6) in the lower body (14). doing.

The upper body (13) is formed so as to project toward the home position (left side in the drawing) from the lower body (14).
A partition plate (15) for partitioning the upper main body (13) and the lower main body (14) is attached inside the image forming apparatus (1).
A paper cassette (16) and a tray (17) are respectively mounted on both side surfaces of the tray. However, the paper cassette (16) is detachably mounted.

In addition, air inlets (18) and (19) are formed on the home position side and the exposure end side of the upper body (13), respectively, and the home position side of the lower body (14) and the copy processing unit (3). Vent holes (10) and (2) on the bottom plate (14a)
0). In this embodiment, the exhaust hole (20) corresponds to the outlet.

The optical system (2) includes a light source (21), a reflecting mirror (22),
(23), (24) and a lens unit (25). The lens unit (25) has a lens (27) and a reflecting mirror (28) mounted inside a casing (26) mounted on the upper surface of the partition plate (15).

Then, the light source (21) and the reflecting mirror (22) are moved at a predetermined speed, and the reflecting mirrors (23) and (24) are moved in the same direction at half the moving speed of the light source (21). As a result, the original placed on the contact glass (11) is exposed, and the reflected light from the original is reflected by mirrors (22), (23),
(24), the lens (27), and the reflecting mirror (28) can be guided to the copy processing unit (3).

In the following description, the light source (21) and the reflecting mirrors (22), (23), (24) are collectively referred to as an optical unit (2 ').

The copy processing unit (3) includes a charging charger (32), a developing device (33), a transfer charger (34), and a peeling charger (3) around a photosensitive drum (31) rotating in one direction.
5), a cleaner (36), and a static elimination lamp (37) are arranged in this order. An electrostatic latent image is formed by irradiation, the toner image is visualized by a developing device (33), the toner image is transferred onto a sheet by a transfer charger (34), and the sheet is exposed by a peeling charger (35). The toner is peeled off from the drum (31), the residual toner is collected by a cleaner (36), and the residual charge is eliminated by a static elimination lamp (37).

The paper transport unit (3) includes a paper feed roller (41) for feeding paper one by one from a paper feed cassette (16), a paper feed path (42),
A registration roller (43) that performs secondary paper feeding in synchronization with the leading edge of the toner image on the photosensitive drum (31) while performing the leading edge correction of the paper in the stopped state, and a paper feeding path (4).
4), Photosensitive drum (31) by peeling charger (35)
The transfer roller (4
5), and a conveyor (46).

The heat fixing unit (5) includes a heat fixing device (51) that heats and fixes the toner image transferred onto the sheet fed by the transport conveyor (46), and a discharge that discharges the sheet onto a tray (17). It has a roller (52). Then, the upstream side of the registration roller (43) and the discharge roller (52)
A paper detection (jam detection) switch (55) is mounted on the upstream side of each.

The suction fan (6) is rotatable inside a first air passage (61) having one end (62) communicating with the upper body (13) and the other end (63) communicating with the exhaust hole (10). And is rotatably driven by a drive source (not shown) so that air can be sucked from the upper body (13) and blown toward the exhaust hole (10). The second air passage is provided continuously with the downstream side of the first air passage (61) and functions as an air passage for taking in a part of the air.
Air passage (65) is provided.

The second air passage (65) is formed in a U-shaped cross section,
A flow dividing plate (66) functioning as an introduction portion with its lower end (66b) facing toward the suction fan (6) with its upper end (66a) facing the first air passage (61). And an upstream end (67a) provided at an appropriate interval inside the flow dividing plate (66), and an intermediate portion is disposed above the heat fixing device (51). And an air blowing guide plate (67) disposed above the conveyor (46). The downstream end (67b) of the blower guide plate (67) is bent so as to approach the transfer conveyor (46) and form a large angle with respect to the transfer direction of the transfer conveyor (46). I have.

The motor for transmitting the driving force to each unit may be of a small output because of the small size of the image forming apparatus (1), and can be mounted outside the side plate (not shown).
No special cooling is required.

In the image forming apparatus (1) having the above configuration, when the power is turned on, the suction fan (6) starts rotating by the driving source. Then, since the suction fan (6) is provided in the middle of the first air passage (61), it sucks the air on the upper body (13) side and downstream of the first air passage (61). Air is blown in the direction of the exhaust hole (10) provided on the side. The air sucked from the upper body (13) by the suction fan (6) as described above is generated by the light source (21), which is a heating element in the optical unit (2 ') provided on the upper body (13) side, and the light source (21). Since the surrounding reflector (22) and the vicinity of the contact glass (11) are cooled, the temperature rises to hot air.

Since the second air passage (65) is provided continuously downstream of the first air passage (61), a part of the warm air sent from the suction fan (6) is divided. The hot air is introduced into the second air passage (65) by the plate (66), and the remaining warm air is discharged out of the machine through the exhaust hole (10). Second ventilation path (65)
The warm air introduced into the air passage passes over the heat fixing device (51) along the air guide plate (67), and further passes through the air guide plate (6).
The end of (7) collides with the conveyor (46) from the end (67b).
Then, the hot air that has collided with the conveyor (46) flows toward the copy processing unit (3), passes therebelow, and passes through the bottom plate (14).
The air is exhausted out of the machine through the exhaust hole (20) formed in a).

Therefore, the warm air flowing through the second air passage (65) raises the ambient temperature above the heat fixing device (51), and also raises the temperature of the air blow guide plate (67) and the parts around it. Further, the water contained in the paper can be evaporated to a certain extent by the warm air colliding with the conveyor (46) and discharged to the outside of the machine.

Therefore, since the paper is preheated before the heat fixing process by the heat fixing device (51), a considerable amount of water is lost, and the generation of water vapor is small when the paper is processed by the heat fixing device (51). . Even if steam is generated, since the ambient temperature above the heat fixing device (51) is high and the temperature of the blow guide plate (67) is high, the steam adheres to the blow guide plate (67) and the like. There is no danger of water droplets, and copy defects caused by water droplets adhering to paper can be effectively prevented.

In addition, since the paper on the conveyor (46) can be pressed against the conveyor (46), it is possible to prevent the leading end of the paper from being curled up, and to more reliably convey the paper by the conveyor (46). be able to. Therefore,
Eliminating the need for a suction fan or the like for bringing the paper into close contact with the lower portion of the transport conveyor (46) eliminates the need for providing a small and inexpensive image forming apparatus.

As the amount of air introduced into the second air passage (65), the entire amount of air sent from the suction fan (6) is discharged through the second air passage (65) to the outside without collision. If it is possible to adopt a structure capable of performing the above, all of the air volume flowing through the first air channel (61) may be introduced.

<Effects of the Invention> As described above, according to the image forming apparatus of the present invention, the air flow exhausted from the cooling device is introduced into the air passage by the introduction unit, so that the air flow is passed through the heating and fixing unit to form a sheet. Since the sheet can be guided to the transport section, it is possible to evaporate water to some extent from the sheet before being processed in the heat fixing section. Therefore, the generation of water vapor can be reduced when the processing is subsequently performed in the heat fixing unit. Also,
Since the ambient temperature around the heating and fixing unit can be increased, even if water vapor is generated in the heating and fixing unit, water droplets do not adhere to components around the heating and fixing unit. Therefore, by using such an image forming apparatus,
It is possible to form a high-quality image by eliminating an image defect due to water droplets adhering to a sheet, that is, an inconvenience of blurring or disappearing of an image.

Also, since only one air passage is provided for guiding the airflow to the paper transport unit, the airflow is guided to the paper transport unit from only one direction. Therefore, it is possible to reliably obtain the pressing force required to press the sheet. As a result, it is possible to prevent the leading end of the sheet from being turned up. This eliminates the need for a special mechanism for adhering the paper,
This can contribute to simplification of the configuration.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of the image forming apparatus of the present invention, and FIG. 2 is a schematic view showing a conventional image forming apparatus. (1) image forming apparatus, (2) optical system, (3) copy processing section, (4) paper transport section, (5) heat fixing section,
(6) Suction fan, (13) Upper body, (14) Lower body, (65) Second ventilation path.

Claims (1)

(57) [Scope of request for utility model registration] 1. An optical system for scanning and exposing a document, an image processing unit for transferring a document image from the optical system, a sheet conveying unit for conveying a sheet on which an image is formed, and a sheet conveying rather than the sheet conveying unit. An image forming apparatus provided on the downstream side in the direction and having a heating and fixing unit for fixing an image transferred to a sheet and having a cooling device for cooling at least the optical system, wherein an air flow exhausted from the cooling device is An introduction section for taking in part or all of the air, an air flow path for guiding the air flow taken in by the introduction section to the heating / fixing section once, and further from the heating / fixing section to a sheet transport path; A discharge port for exhausting the airflow guided to the paper transport path by the outside of the apparatus, and as an air blowing path for guiding the airflow to the paper transport path,
An image forming apparatus comprising only the air passage.